High performance has always been and continues to be the calling card for flash storage. But many flash arrays use legacy storage interfaces and protocols that were designed for slower hard-disk drives (HDDs). Because the read/write arm moving across the spinning disk creates multiple milliseconds of latency, there’s no way for an HDD to keep up with a system’s CPU. In light of that, HDD interfaces use caching and other techniques to minimize the number of read and write operations.